Secondary radiation exposure

My mother in law got a cancerous lump taken out of her left breast a few months ago, as well as the lymph nodes under her left arm. She is currently receiving chemotherapy (3 weeks cycles) and will be doing her last cycle in January. After that, the doctors are planning to give her
radiation therapy.

We live right next door to her and have frequent contact. I am 25, mom of a 2 years old and planning to try to conceive again in a few months. I hate to sound egoistic, but am very worried for our health while she'll be undergoing radiation treatment. I read a very informative article on this site that gave someone with thyroid cancer guidelines on how many days after the therapy he should wait to perform certain activities, including eating with people and other interactive activities. His therapy was different from the one my mother in law will receive, so I'd like to know what are the guidelines in this case.

Thanks you so much in advance for any information you might be able to give me.

There are different kinds of radiation as well as different kinds of radiation treatments. One form of radiation treatment is for the patient who goes to the hospital daily for a number of weeks to receive a series of radiation treatments as an outpatient. Sometimes this form of radiation treatment is called external beam radiation treatment. This type of radiation treatment does not cause any potential secondary radiation exposure problems to family members, even young children. This is the type of radiation that your mother-in-law is likely to receive, so you need not worry about exposing your children.

In contrast, the type of radiation treatment used for thyroid disease is often very different. Here, the patient drinks a radioactive agent that is accumulated in the thyroid. This radioactive agent then gives off radiation, mainly to the thyroid gland, but also to anyone near the patient. After a period of time (determined by the patient's physician), the amount of radiation decreases (decays) to safe levels for other people.